Shishaldin volcano is one of the most active volcanoes in the Aleutian arc, erupting at least 28 times since 1775. The previous eruptive period occurred in late 1995 and early 1996 and consisted of minor explosions that produced low-level steam and ash emissions. The recent eruptive period began in mid-February of this year, producing an ash cloud to at least 45,000 ft ASL on April 19, 1999. Since that time several ash plumes as high as 20,000 ft ASL have extended as far as 500 miles from the volcano. The last eruptive activity occurred on May 27. Since then, seismic levels have remained low and no thermal anomalies or plumes have been observed in satellite imagery.

Shishaldin volcano is located near the center of Unimak Island in the eastern Aleutians. The spectacular symmetric cone has a base diameter of approximately 10 miles (16 km) and a small summit crater that typically emits a steam plume with occasional small amounts of ash.

Information specifically about Shishaldin is below. This link leads to updates on other Alaska and Kamchatka volcanoes. The following links lead to general, background information on Shishaldin Volcano:

General Description; File Photographs; Bibliography; Past Activity; Downloads

Level of Concern Color Code: GREEN
Last Level of Concern Color Code: YELLOW

The last eruptive activity occurred on May 27. Since then, seismic levels have remained low and no thermal anomalies or plumes have been observed in satellite imagery. We are lowering the Level of Concern Color Code to GREEN based on the decline in activity over the past month. AVO will continue to closely monitor Shishaldin with seismic and satellite data.

Level of Concern Color Code: YELLOW

Seismicity levels at Shishaldin remained low this week, and although the top of the volcano was visible on several occasions no ash plume or thermal anomaly was seen in satellite imagery. However, low levels of seismicity persist beneath the volcano, suggesting that explosive activity is still possible with little or no warning. For this reason the Level of Concern Color Code is being kept at YELLOW. AVO continues to monitor the situation 24 hours a day with seismic and satellite data.

Level of Concern Color Code: YELLOW

Seismicity levels at Shishaldin remained low this week, and although the top of the volcano was visible on several occasions no ash plume or thermal anomaly was seen in satellite imagery. However, low levels of seismicity persist beneath the volcano, suggesting that explosive activity is still possible with little or no warning. For this reason the Level of Concern Color Code is being kept at YELLOW. AVO continues to monitor the situation 24 hours a day with seismic and satellite data.

Level of Concern Color Code: YELLOW
Previous Level of Concern Color Code: ORANGE

Over the last several days seismicity levels remained low, and although the top of the volcano was visible no ash plume or thermal anomaly was seen in satellite imagery. The Level of Concern Color Code is therefore being downgraded to YELLOW. However, low levels of seismicity persist beneath the volcano, suggesting that explosive activity is still possible with little or no warning. AVO continues to monitor the situation 24 hours a day with seismic and satellite data.

May updates
April updates
March updates
February updates

ABBREVIATED COLOR CODE KEY (contact AVO for complete description)
GREEN -- volcano is dormant; normal seismicity and fumarolic activity occurring
YELLOW -- volcano is restless; eruption may occur
ORANGE -- volcano is in eruption or eruption may occur at any time
RED -- significant eruption is occurring or explosive eruption expected at any time

RECORDING OF THE STATUS OF ALASKA'S VOLCANOES (907) 786-7478

CONTACT INFORMATION:
Terry Keith, Scientist-in-Charge, USGS tkeith@tundra.wr.usgs.gov (907) 786-7443
John Eichelberger, Coordinating Scientist, UAF-GI eich@gi.alaska.edu (907) 474-5530

The Alaska Volcano Observatory is a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys.